The present invention relates to a method for forming a nozzle employed in continuously casting for the purpose of obtaining a mold member of a submerged nozzle, a long nozzle or the like.
In general, the nozzle employed in continuously casting is constituted by employing various powdered refractory materials having different characteristics in a body portion, an edge portion, an inner hole portion, and a powder (slag line) portion in accordance with a necessary function on practical use. A mold member of a conventional nozzle of this type is obtained through a process of filling with necessary powdered refractory materials regulated in grain size one after another while employing a suitable dividing plate inside a rubber mold charging a mandrel (metal mold), and then pressing with hydrostatic pressure.
Particularly, as shown in FIG. 9, a lower end portion of a cylindrical rubber mold 21 is blocked with a disk-shaped rubber mold 22. A mandrel 23 is charged into the cylindrical rubber mold 21, so that a cylindrical mold hole is formed between the cylindrical rubber mold 21 and mandrel 23. A powdered refractory material 25 for the edge portion is filled to a predetermined height inside the cylindrical mold hole, while employing a hopper 24 mounted on an upper end portion of the cylindrical rubber mold 21. Furthermore, a powdered refractory material 26 for the body portion is filled to a predetermined height.
At the next step, a cylindrical dividing plate 27 is concentrically arranged on an outer periphery of the mandrel 23, so that a cylindrical space is formed between the dividing plate 27 and mandrel 23. A powdered refractory material 28 for the inner hole portion is filled to a predetermined height inside the cylindrical space, while employing a hopper (not shown) mounted on an upper end portion of the dividing plate 27. Furthermore, the hopper is removed, and then an upper end portion of the dividing plate 27 is blocked with a disk-shaped dividing plate 29.
At the further step, the cylindrical dividing plate 27 is concentrically arranged on an outer periphery of the mandrel 23. A powdered refractory material 28 for the inner hole portion is filled to a predetermined height inside a cylindrical space formed between the cylindrical dividing plate 27 and rubber mold 21, while employing a hopper 24 mounted on a upper end portion of the rubber mold 21. Furthermore, a powdered refractory material 30 for the powder portion is filled to a predetermined height, and then the powdered refractory material 26 is filled to the height equal to the powdered refractory material 28 for the inner hole portion.
Next, after the disk-shaped dividing plate 29 is removed and the cylindrical dividing plate 27 is released, the powdered refractory material 26 for the body portion is filled to a predetermined height. Furthermore, as shown in FIG. 10, the upper end portion of the cylindrical rubber mold 21 is blocked with the disk-shaped rubber mold 31, and then each powdered refractory materials is formed by pressing with hydrostatic pressure.
As shown in FIG. 11, each of the rubber molds 21, 22 and 31 is released after pressing with hydrostatic pressure. The mandrel 23 is further released, so that a mold member 32 for the continuous casting nozzle is formed as shown in FIG. 12. Finally, the mold member is mechanically processed into the nozzle employed in continuously casting by machining appearances and holes thereon after firing.
However, the conventional method for forming the nozzle employs the dividing plates for filling each powdered refractory material at the necessary position as described above. Therefore, there is a problem that the forming process is complicated, and the powdered refractory materials segregate at boundary portions thereof, due to releasing of the dividing plates. Moreover, there is another problem in that the powdered refractory material for each portion is incorrectly arranged.